Electric-switch guard.



SSS. THOMPSON & E. J. LE BLOND.

ELECTRIC SWITCH GUARD.

APPLICATION FILED MAY 15. I916- 1 ,247, 1 8O Patented Nov. 20, 1917';

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ELECTRIC SWITCH GUARD. I APPLICATION FILED HAY I5, I9I 5- I 1,247,180. I Patented Nov. 20, 1917;

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UNITED STATES PATENT OFFICE.

SAMUEL S. THOMPSON AND EDMOND J. LE BLOND, 0F MINNEAPOLIS, MINNESOTA.

ELECTRIC-SWITCH GUARD.

Specification of Letters Patent.

Patented Nov. 20, 191 '7.

Application filed May 15, 1916. Serial No. 97,532.

To all whom it may concern:

Be it known that SAMUEL S. THOMPSON .and EDMOND J. LE BLOND, citizens of the United States, residing at Minneapolis, in

the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Electric-Switch Guards, of which the followingis a specification. 1

Our invention relates to electric switch guards for preventing theft of the electrical currents at service terminals and has for its object to provide in combination with the usual service box a supplemental casing which may be placed within the service box over the line switch and fuse block so as to render exposed parts inaccessible, and thus prevent the use of jumpers or other devices and tampering with the fuse blocks so as to obtain current without actuation of the watt-hour meter. A further object is to form the casing so that it is adjustable in length to fit within any service box over any size fuse block and switch so that the same can readily be attached to an existing structure of the kind mentioned without altering A still further object is to provide means in combination with the'guard whereby the line switch may be operated from outside the guard without exposing any of-the parts.

The full objects and advantages of our invention will appear in connection with the detailed description thereof and'are particu. larly pointed out in the claims. In the drawings, illustrating the application of our invention inone orm,-

Figure 1 is a plan view of a service cabinet with our invention applied thereto. Fig. 2 is a sectional elevational view taken substantially on line 2-2 of Fig. 1. Fig. 3 is a perspective view of the casing proper of our invention segregated from the service cabinet. Figs. 4 and 5 are wiring diagrams of electrical service terminal circuits showing the common methods of procuring the current at the expense of the producer.

Fig. 4 shows a common form of three-wlre service terminal with the watt-hour meter connected in the usual manner. Each of the three-line wires 10, 11 and 12 are connected to independent fuses 13, 14 and 15 which lead to a knife switch 16. The outer blades of switch 16 are connected by leads 17, 18 to current coils 19 and 20 of a wattmethods is made impossible. covering these parts and its special features hour meter 21 which has the potential coil 22 thereof connected across said leads. The sald current coils are further connected by leads 23 and 24: to fuses 25 and 26 of a branch block 67, and the center blade of switch 16 is connected to both of the remaining fuses 27 and 28 of said branch block by a lead 29. The most common method employed in stealing current is to unscrew or loosen one of'the fuses 13 or 15. In so doing the pres sure coil 22 and the corresponding current coil of the watt-hour meter 21 is cut off from the line, rendering the meter inoperable. Current may then be tapped off from the opposite sideof the line without registering upon the watt-hour meter. A similar effect may be produced by attaching a shunt, shown in dotted lines in Fig. 4, at 30 to one blade of the knife switch 16 and to the fuse 25. When the corresponding side of the line is'used a small portion of the current passes through the watt-hour meter and is registered thereby and the major portion of I the'current passes through the shunt 30 and is not registered. By covering up the fuses 13, 14 and 15 and the knife switch 16 and all bare terminals leading to and from them, the theft of current by these and similar The casing for will be presently explained.

A two-wire service terminal and the method for shunting the current from the watt-hour meter is shown in Fig. 5. Line wires 31 and 32 are connected with fuses 33 and 31 which are further connected with a knife switch 35 in the usual manner. A watt-hour meter 38 is connected "into the load by having-its current coils 37 cut in on one of the load wires 36 and its potential coil 39 connected across the line wires 36 and 40. One of the line wiresis usually grounded and in most cases is the wire 31,

current from which does. not pass through the current coil of the meter. By reversing the connections of the load wires 36 and 40 at'the knife switch 35 as indicated in dotted lines in Fig. 5, and by grounding the wire 36 on the other side of the meter, the current is shunted away from the current coils of the meter throu h the ground and only a small percentage 0% the same is registered by the meter. Inclosing switch 35 hence renders theft by this method impossible.

' 27 and 28.

The service terminal cabinet employed with the system illustrated in Fig. 4 is shown in detail in Figs. 1 and 2 w1th our casing member applied thereto. A cabinet box 42 provided wlt-h a hinged cover 43 has situated-in it a switch block Y44 and the branch block 67 carrying the fuses 25, 26, Block 44 has mounted on it the knife switch 16 and the set of line fuses 13, 14 and 15 which are clearly indicated in that figure. This latter block is completely covered by the casing shown in Fig. 3. A rectangular box member 46 open at one end and at the bottom has secured to it a similar box member 47 also open at one end and at the bottom, which member laps over member 46 and is secured thereto by a number of clencher rivets 48 which may be inserted in any of a number of alined corresponding holes 49 in said box members. The member 47 is provided with a cover 50 hinged to it at 51 having a raised central portion formed withsloping sides 52 and 53. The casing thus formed is placed over the switch and fuse block 44, as clearly shown in Figs. 1 and 2, and is held in place by a pair of angles 54 which are adapted to slide under the block 44 and be secured to the box proper by one of the rivets 48, as shown in dotted lines in Fig. 3. It will be noted in Fig. 8 that the box is formed with legs 55. This permits the leads from the block 44 to pass out through the device in the space between said legs without being disturbed. WVhendesired the sides of the box may be partially perforated to form knockouts at 56 drawn out through the same. The manner of securing the cover 50 in place is best shown in Fig. 1. A hook 57 is pivoted to the sloping slde 53 of cover 50 and is adapted to engage a staple 58 secured to the box member 47 and projecting through said cover. Hook 57 may be locked in place' by a seal 59 in the usual manner.

The switch operating mechanism is most clearly shown in Figs. 1 and 2. The handle usually provided on knife switches is removed from switch 16 and two screw eyes 60 are screwed into the switch bar 61 in place thereof, as clearly indicated. These eyes are adapted to receive a wire handle 62 comprising a looped portion 63, a neck 64 and outspreading arms 65 which pass directlythrough said eyes. The neck 64 of said handle is arranged to pass through a hole 66 in the sloping side 52 of the box cover 50. When the switch is closed the handle takes th position indicated in full lines in Fig. 2 with the loop 63 resting upon the side 52 of the box cover 50. By drawing out the handle by means of said loop the switch may be opened as shown in dotted lines in Fig. 2, and due to a slight bend 67 in said handle the same may lie fiat upon permitting additional leads to be 1 locl the top of the box proper, cabinet door to close in either the open or closed position of the switch. In this manner the switch may be opened or closed without opening the cover 50, thus concealing the live parts of the systemat that point and permitting the line switch to be operated without interfering with the protective device.

The advantages of our invention are manifest. The device is very simple and inexpensive to manufacture. The line may at any time be cut off from the service terminal without interfering with the protective device. The casing may be installed and employed with any form of existing allowing the structure without altering or modifying the same.

We claim:

1. In combination with a service boxhaving a line switch and fuse block therein, a secondary casing positioned within the service box to cover the line switch and fuse block, means for securing said casing within the service box, a door on said casing, and means for locking the door in closed position. 2. In combination with a service box havmg a lme switch and fuse block therein, a secondary casing positioned within said box to cover said switch and fuse block, means on the casing adapted to engage the switch and fuse base to hold the casing in place, and means for locking said casing and holding means from being removed.

3. In combination with a service box having a line switch and fuse block therein, a. secondary casing positioned within said box to cover said switch and fuse block, means within the casing adapted to engage the switch and fuse base to hold the casing in place, a cover for said casing, and means for ring the cover in closed position.

4. In combination with a service box having a line switch and fuse block therein, a casing positioned within the box to cover said switch and fuse block, a pair of angle pieces having a leg positioned under the switch base and another leg extending along the inner sides of the casing, and means for securing the angle pieces to the casing after the same has been positioned within the box.

5. 'In combination with a service box having a line switch and fuse block therein, a secondary casing positioned within the box to cover said switch and fuse block and secured to the switch base, a cover for said casing having an inclined wall, and a switch-operating member connected with said switch and extending through the inclined wall of said cover.

6. In combination with a service box having a line switch and fuse block therein, a secondary casing positioned within the box to cover said switch and fuse block, a cover for said casing having an inclined wall, and a looped wire member for operating the switch passing through said inclined wall and having its ends outspread and pivoted to the switch.

7. In combination with a service box having a line switch and fuse block therein, a secondary casing positioned within the box to cover said switch and fuse block comprising a pair of telescoping members, and means for securing said sections together in various extended positions.

8. In combination with a service box having a line switch and fuse block therein, a secondary casing positioned within the box v to cover said switch and fuse block comprising a pair of telescoping members, means for securing said sections together 1n varlous extended posltions, and means connected to both of said members for securing the casing to the switch base.

'9. In combination with a service box having a line switch and fuse block therein, a secondary casing positioned within the box to cover said switch and fuse block comprising a pair of telescoping members, and means for securing said sections together in variousextended positions, one of said members having a door Within an inclined wall and a member passing through said wall for operating a switch.

In testimony whereof We aflix our signa- I tures in presence of two witnesses.

SAMUEL S. THOMPSON. I EDMOND J. LE BLOND. Witnesses:

F. A. WHITELEY, H. A. Bowman 

